PROJECT SUMMARY: The goal of this proposal is to determine the role of sensory neuron Nucleotide-Binding Oligomerization Domain, Leucine Rich Repeat And Pyrin Domain Containing 3 (NLRP3) inflammasome in postoperative pain. Acute postoperative pain is experienced by 80% of patients, where 43% of these patients still experience pain even after receiving the most current analgesic treatments. Twenty percent of patients out of the 80% develop chronic postoperative pain. Postoperative pain significantly impacts the outcome of patients by inhibiting them from performing rehabilitative exercises, which leads to increased hospital stays and longer recovery times. Postoperative pain is both inflammatory and neuropathic, which results in mechanical and thermal peri- incisional hypersensitivity. The NLRP3 inflammasome is known to be proinflammatory because it induces the release of the inflammatory and pain-inducing cytokine interleukin-1? (IL-1?). In addition, NLRP3 activation requires toll-like receptor 4 (TLR4) stimulation, which is known to sensitize the pain-modulating receptor transient receptor potential vanilloid 1 (TRPV1) on sensory nerve terminals. Importantly, IL-1?, and TRPV1 sensitization have been linked to mechanical and thermal hypersensitivity in animal models of postoperative pain. However, there is little known about the role of NLRP3 in sensory neurons and how NLRP3 activation contributes to postoperative pain. Therefore, this proposal will elucidate the mechanisms of NLRP3 activation after surgical incision, and how NLRP3 activation and TRPV1 sensitization contribute to the generation of postoperative pain. To achieve this, the project includes both molecular and physiological methods such as quantitative polymerase chain reaction, enzyme-linked immunosorbent assay, calcium imaging, ex vivo teased fiber recordings, and behavioral assays. Aim 1 will determine the role of the NLRP3 inflammasome in DRG neurons after perioperative incision and identify the mechanism of DRG neuron NLRP3 activation. Aim 2 will test the involvement of neuronal NLRP3 inflammasome activation in TRPV1-mediated sensitization to mechanical and thermal stimuli after perioperative incision. Since this proposal studies the mechanisms underlying postoperative pain, its aims fall under the NINDS mission of reducing the burden of neurological and painful diseases.